The present invention relates to a slide guide device having a self-aligning mechanism which, even if an eccentric load acts on the slide, the slide operates smoothly. The present invention further relates to a knockout device for removing a press worked product from within a die. The present invention also relates to a press machine which is equipped with a slide guide device and a knockout device for removing the pressed worked product. Such a press machine is especially suitable for high precision molding of parts, particularly cold extrusion parts, punched parts, drawn parts, and the like.
Innovations to make the sliding of the slide and guide post smooth, to ensure the product precision of the press products, or to absorb unbalanced loads on a slide and heighten the dynamic precision, are constantly being conducted for press machines and the like. Currently, however, a satisfactory mechanism has yet to be achieved.
In Japanese Laid-Open Patent Publication Number 8-206895, a slide guide device for a press machine has a plurality of guide posts provided at appointed locations of a slide. The plurality of guide posts supports a vertically oriented base shaft part in a freely rotating manner. An eccentric shaft part, which is unbalanced by a constant eccentricity amount with respect to this base shaft part, extends downward from the plurality of guide posts. A plurality of guide blocks are separately attached opposite each of the guide posts. The plurality of guide blocks guides the eccentric part in the vertical direction in a freely sliding manner. The guide blocks are disposed so that the direction of eccentricity of the eccentric shaft part with respect to the base shaft part of each of the guide posts has an angle relationship with respect to the thermal expansion direction of the slide so that, while the center of the slide is maintained at a constant position, the slide is guided in the vertical direction in a freely moving state. A slide is guided in a freely moving state in the vertical direction by the plurality of guide posts.
In Japanese Laid-Open Patent Number 8-174294, a slide gib is multiply divided in the shaft line direction from the center of a long material having a cylindrical central hole. In addition, the inner perimeter surface oft he central hole is made to be a sliding surface. The liner is multiply divided in the shaft line direction from the center of a cylinder. The outer perimeter surface of the cylinder is made to be a sliding surface. The dynamic precision is improved by minimizing the mis-alignment of each of the upright and the slide.
However, with the former slide guide device, the displacement of the slide is absorbed by making the center of the base shaft part of the guide post capable of moving horizontally with respect to the center of the eccentric shaft part in the direction of displacement resulting from thermal expansion. When an eccentric load acts on the slide, the bending stress on the eccentric shaft parts at the four comers is unavoidable. Because of the action of a twisting torque, a smooth vertical motion of the slide can not be anticipated, and, therefore, it is difficult to bring out the precision of the die.
The latter example is constructed so that the slide gib and the liner make contact in the radial direction at the arc surface. However, because it is a member which is long in the shaft direction, and there is a line contact or a surface contact in the shaft direction, even if the eccentric load in the rotation direction is absorbed, absorbing the eccentric load in the shaft direction remains difficult.
A knockout device for a press machine is a necessary mechanism for removing a product which has been worked in a press. Knockout devices are widely used irrespective of the type of press.
A conventional construction for a knockout device is described in Japanese Laid Open Patent Publication Number 6-126368. In this embodiment, a lower holder, anchoring a die, is affixed o a top surface of a bolster. A through hole is formed in the center of the lower holder and bolster. A mandrel transfer pin is inserted through this hole. The knockout pin moves vertically due to a roller which abuts against the lower end of this pin. Furthermore, this roller is linked with a cam mechanism through a third link mechanism.
In Japanese Laid Open Patent Publication Number 9-285830, a knockout device is disclosed which has a knockout pin guided by a case and a taper block.
However, with the former construction, the roller pivots along the path drawn by the end of a pivoting link member having one end as the support point. Therefore, the contact point with the knockout pin moves with the position of the roller. In addition, the knockout pin also moves, and, as a result, it is difficult to always push up perpendicularly. Problems arise in which this becomes mechanical vibration or becomes a sliding load and requires a large amount of energy for the motion.
With the latter, the roller still moves along the movement pathway of the knockout lever as in the former example. The roller does not have a construction wherein the center of the knockout pin is always being pushed up at the time of knockout. Therefore, as a matter of course, a bending stress acts on the knockout pin, and a smooth motion with the case is not achieved. The same problems as described above are also a concern.
It is an object of the present invention to provide a slide guide device wherein, even if an eccentric load acts on a slide, self-alignment is possible and movement is conducted smoothly.
It is a further object of the present invention to provide a knockout device for a low noise, energy conserving press machine wherein knockout requires a small amount of energy and operation is conducted under an always stable knockout load.
It is still a further object of the present invention to provide a simple construction for a press machine with excellent eccentric load resistant properties and with a high working precision.
Briefly stated, there is provided a middle liner of a slide guide device for a machine press having a spherical shaped side which fits into a sliding gib attached to a slide. The middle liner slides along a fixed gib first and second linear surfaces at an angle with each other. Self-alignment and smooth movement of the slide is achieved even when an eccentric load acts on the slide. A machine press equipped with such a slide guide device has excellent eccentric load resistance and high working precision. A press machine is further equipped with a knockout device having knockout block moving between a pair of guide rails. A plurality of middle liners, having at least one spherical surface, are positioned between the knockout block and the guide rails. The resulting knockout device provides a stable knockout load with low noise and low energy consumption.
According to an embodiment of the present invention, there is provided a slide guide device comprising: a sliding member; at least first and second fixed gibs disposed on opposite sides of the sliding member; at least first and second sliding gibs attached to the sliding member; a middle liner on the at least first and second sliding gibs, slidably contacting the at least first and second fixed gibs; and the middle liner having a spherical contact on a first side with one of the fixed gibs and the sliding gibs, and a planar contact on a second, opposite side with the other of the fixed gibs and the sliding gibs.
According to another embodiment of the present invention, there is provided a knockout device for a press machine having a slider with a die attachment surface, comprising: a lower holder opposite the die attachment surface; a knockout pin passing through the lower holder; a knockout block which knocks out the knockout pin; at least first and second guide rails disposed at opposite sides oft he knockout block; means for moving the knockout block along the at least first and second guide rails; and a plurality of middle liners, having at least one spherical surface, between a side surface of the knockout block and the at least first and second guide rails.
According to a feature of the present invention, there is provided a press machine, comprising: a sliding member; at least first and second fixed gibs disposed on opposite sides of the sliding member; at least first and second sliding gibs attached to the sliding member; a middle liner on the at least first and second sliding gibs, slidably contacting the at least first and second fixed gibs; and the middle liner having a spherical contact on a first side with one of the fixed gibs and the sliding gibs, and a planar contact on a second, opposite side with the other of the fixed gibs and the sliding gibs.
One embodiment of the present inventions is drawn to a slide guide device, wherein a middle liner, in which one side has spherical contact and the other side has a plane contact, is disposed between a fixed gib and a slide gib.
Preferably, the present invention is drawn to a slide guide device, wherein the plane contact surface of the middle liner comprises two orthogonal surfaces and contacts with the fixed gib.
More preferably, the present invention is a slide guide device, wherein the middle liner forms, in a shell-shape, two plane contact surfaces which intersect orthogonally on the interior.
Even more preferably, the present invention is a slide guide device, wherein a recessed part is formed on a ridge line on the orthogonal surfaces of the middle liner.
Even more preferably, the present invention is a slide guide device, wherein the construction positions the rotation center of the middle liner at the center of the slide surface.
Another embodiment of the present inventions is drawn to a press machine. The press machine has a fixed gib, which is disposed in a fixed manner at four corners of the perimeter, and a middle liner, which is disposed between the fixed gib and slide gib, contributing to the movement of the slide. The middle liner is in spherical contact with the slide gib on one side, and the other side is in contact with the fixed gib by two orthogonal planes.
Preferably, the present invention is drawn to a press machine, wherein the slide is constructed from an upper slide, which moves vertically in response to the screw action of a rotation screw shaft, and a lower slide, which is joined to the upper slide and fits with the screw shaft so that there is play therebetween. A middle liner is disposed at the top and bottom four corners of each of the slides.
More preferably, the present invention is drawn to a press machine, wherein a nut joins to the upper slide which screws onto the screw shaft. The nut contacts the lower slide with a spherical surface. The upper and lower slides are joined by a screw.
One embodiment of the present invention is achieved by a knockout device for a press machine. The knockout device has a lower holder disposed opposite a die attachment surface of a vertically moving slide. A knockout pin passes through the lower holder. A knockout block, for knocking out the knockout pin is provided in the knockout device. A plurality of middle liners, having at least one surface as a spherical surface, is disposed between a side surface of the knockout block and a pair of guide rails, which is disposed and affixed opposite the block side surface. The middle liners guide the knockout block.
Preferably, the present invention is achieved by a knockout device, wherein the guide rail is tubular or cylindrical and is in surface contact with the other surface of the middle liner.
More preferably, the present invention is achieved by a knockout device, wherein the guide rail is a triangle pole and is in two surface contact with the other surface of the middle liner.
Even more preferably, the present invention is achieved by a knockout device, wherein the lower end of the knockout block is pivotably connected via an eccentric pivoting mechanism to one end of a knockout lever whose other end is connected to a motion source which moves vertically.
One embodiment of the present invention is achieved by a knockout device for a press machine. The knockout device has a lower holder disposed opposite a die attachment surface of a slide which moves vertically. A knockout pin passes through this lower holder. A knockout block knocks out the knockout pin. A plurality of middle liners are disposed between a side surface of the knockout block and a pair of guide rails which are disposed and affixed opposite this block side surface. The lower end of the knockout block connects in a pivotable manner via an eccentric pivoting mechanism to one end of a knockout lever whose other end is connected to a motion source which moves vertically. The motion source is a double acting double rod hydraulic cylinder. This cylinder, by a variable hydraulic pump which is driven by a motor, compresses and controls oil, which is supplied from a hydraulic tank. Rotational energy is stored between the hydraulic pump and the motor. A fly wheel is provided via a clutch which is opened and closed by an external control.
Preferably, the present invention is achieved by a knockout device, wherein, after the rotational energy of the motor is stored in the fly wheel, the rotational energy is supplied to the hydraulic pump via the clutch which opens and closes by an external control.
More preferably, the present invention is achieved by a knockout device, wherein, when the oil pressure inside the hydraulic supply circuit exceeds a preset standard value, a pressure control valve operates and oil is guided to the tank.